Answer:
432 million.
Step-by-step explanation:
We are given that,
Number of mobile users today = 540 million.
Increase in the number of users each year = 20%.
Let, the number of users last year = x million.
So, the number of users increase from the last year are '20% of 540 million' i.e. = 108 million.
Thus, the number of users in the last year = Number of user's today - Number of users increased.
i.e. number of users in the last year = 540 - 108 = 432 million.
Hence, there were 432 million mobile users last year.